Grapes and raisins can be toxic to dogs. While the toxin is unknown at this time, grape ingestion by dogs can be a serious problem as grapes are toxic to dogs. Even eating a very small amount has the potential to cause toxic, potentially fatal effects. The toxic is characterized as being nephrotoxic, which means grapes and raisins can cause kidney failure. There is no antidote for grape poisoning in animals so very prompt treatment is required.

Why are grapes and raisins toxic for dogs?

The toxin in grapes and raisins is nephrotoxic, which can lead to kidney failure in dogs. The exact toxin has yet to be identified but it appears dogs are the most at risk compared to other species such as cats.

How many grapes or raisins can your dog eat and what is the toxic dose?

Symptoms of grape toxicity have been reported with ingestion of 0.7 oz/kg of grapes and 0.11 oz/kg that of raisins. An average-sized seedless grape weighs approximately 0.2 ounces. Therefore, the toxic dose of grapes for a 10kg dog would be 7 ounces or 35 grapes. However, the toxic dose definition is presently shifting, with lower doses now considered to be harmful. Because every dog has a different threshold to toxicity when it comes to grapes and raisins, you should assume that any amount of grape or raisin ingestion can be toxic and harmful to dogs of any bodyweight.

Not every dog or cat is affected by grapes and raisins. Many species can consume significant amounts of grapes or raisins without issue. Nobody knows the patient's risk factors (besides ingestion).

How is grape and raisin toxicity diagnosed?

No specific diagnostic test exists for grape and raisin toxicity. Diagnosis is based on a history of exposure to grapes or raisins and the development of acute kidney failure. Therefore, it is critically important to provide your veterinarian with all the details possible and if there could have been exposure to grapes or raisins.

What are the signs and symptoms of grape and raisin toxicity in dogs?

The clinical symptoms of grape or raisin ingestion are related to kidney failure as this is how the toxin works. Within several hours of ingestion, clinical symptoms usually begin. Vomiting has been reported in all cases. The vomitus will usually contain eaten fruit. In addition, clinical signs that are seen within the first 24 hours include:

  • diarrhea (± skin of the grapes)
  • lack of appetite (anorexia)
  • abdominal pain
  • hypersalivation
  • lethargy

Clinical signs that appear 1-5 days after ingestion include:

  • Increased thirst and urination
  • loss of coordination (ataxia)
  • trembling

As renal failure develops, the dog will have none to very little urine production.

What is the treatment for grape or raisin toxicity in dogs?

If ingestion is recent and your dog hasn't vomited, we recommend inducing vomiting. Your veterinarian will have a safe, predictable medication to induce vomiting. Alternatively, you could use hydrogen peroxide (maximum 45mLs) to induce vomiting. This should only be tried once and if your dog has not already vomited. There are various dangers associated with administering hydrogen peroxide, including significant esophageal and gastric irritation.

If induction of vomiting is unsuccessful or if ingestion hasn't been recent, and if your dog is not showing any clinical signs, your veterinarian may administer activated charcoal. Activated charcoal will help bind any toxins in the intestines to prevent absorption.

If your dog is already showing symptoms of kidney failure, hospitalization with intravenous fluids should be performed. This will help support the kidneys after the toxic insult. Length of hospital stays will vary depending on the clinical symptoms and blood work findings.

FAQs about grape and raisin toxicity in dogs

Is grape seed extract or grape juice toxic to dogs?

It doesn't appear to be harmful. Seedless grapes have been linked to toxicity, so there's no reason to suspect the toxin is within the seeds. Then it's conceivable that grapeseed extract is safe to use.
There is no mention of grape juice in studies. However, because we don't know what the poisonous substance is, or if heat will destroy it, feeding dogs or cats grape juice right now is not recommended.

How common is grape toxicity in dogs?

It is not known how common grape toxicity is in dogs. However, with the increasing popularity of grapes and raisins as snacks for people to feed their dogs, there will be more cases presented at veterinary hospitals.

How long does it take to show grape or raisin toxicity and how long does it last?

The time to onset of clinical signs takes several hours, with a range from 30 minutes up to 24 hours. Clinical symptoms usually begin within an hour of ingestion. The toxin is nephrotoxic (toxic to the kidneys), which means that damage can occur rapidly and dogs often don't recover well if they develop renal failure as a result.
The length of time it takes your dog to recover depends on when you begin therapy, as well as if he or she has any residual kidney damage. In some cases, dogs will have permanent kidney damage and in others, they may recover completely. Unfortunately, there is no one answer as every dog responds differently.

Is tartaric acid the cause of grape and raisin toxicity in dogs?

The ASPCA Poison Control has investigated this and has said:

"Potassium bitartrate is the salt of tartaric acid, and both potassium bitartrate and tartaric acid are uniquely present in high concentrations in grapes and tamarinds. Older studies have demonstrated species differences in absorption, elimination, and toxicity of tartaric acid and its sodium salt, potassium sodium tartrate (Rochelle salt), with dogs identified as having substantial absorption and rapid, high renal elimination."

How do you know if your dog has eaten grapes or raisins?

This can be difficult to determine. If your dog has been vomiting, look closely at the vomitus to see if you can find any pieces of grapes within. Also, if your dog has diarrhea, look for signs of grape skin as this suggests your dog has ingested grapes and you should seek veterinary advice as soon as possible.

If my dog is showing clinical signs, what should I do?

If your dog is showing clinical signs, contact your veterinarian as soon as possible. Time is of the essence when it comes to grape and raisin toxicity. Even if you can't find any grapes or raisins in your dog's vomit or feces, that doesn't mean they haven't ingested them. The toxin can be rapidly absorbed and cause damage to your dog's kidneys.

If my dog is showing no clinical signs, what should I do?

Don't panic! If the ingestion was fairly recent and you have caught it early enough (within a few hours of ingesting), then your veterinarian may be able to administer activated charcoal if there are still grapes or raisins in the stomach. This will help to bind the toxin and hopefully reduce any further damage. However, not all dogs that ingest grapes or raisins develop clinical signs.
To be sure, it is best to monitor your dog closely for the next 24-72 hours if they have ingested grapes or raisins to see if they develop any clinical signs. If they don't, then you can breathe a sigh of relief!

If my dog ate a small number of grapes or raisins within the last hour, can I induce vomiting?

If your dog hasn't already vomited, then yes, inducing vomiting is recommended. Contact your veterinarian since inducing vomiting with hydrogen peroxide has a higher risk of side effects than using medicine your veterinarian would use.

Grape and raisin ingestion can be a serious problem for dogs. Grapes are toxic to dogs, but the specific toxin is unknown at this time. Dogs that develop kidney failure as a result of eating grapes or raisins have a poor prognosis. It appears while some dogs can safely eat grapes and raisins, a very small amount has the potential to cause toxic effects on your dog's kidneys. The toxins in grapes are nephrotoxic (toxic to the kidneys), which means they will damage rapidly if not taken care of immediately by seeking veterinary advice as soon as possible after ingesting any quantity!  If you think your dog may have eaten grapes or raisins, contact your veterinarian ASAP!